A well?proven and recommended high?vacuum grease for electron beam instruments. Grease L is a petroleum hydrocarbon grease, containing no additives. Very low vapour pressure (@20°C of 8x10^?¹¹ torr), high vacuum grade. Type L is widely used in electron microscopy where moderately high column temperatures and high vacuum requirements demand a vacuum grease with extraordinary characteristics. Type L is also used in the stationary phase of gas liquid chromatography, and may be used on all ground joints in a vacuum system (not for stopcocks). Its solubility is as follows: in ethanol at 20°C?0.003%; 60°C?0.005%; 100°C?0.011%; 150°C?0.011%. Grease L softens and melts at about 47°C and it is not recommended for joints where temperatures exceed more than 30°C in use. Grease T is recommended for these higher temperatures.